Differences in Octane

[t4thfavor]

I towed my camper a few hundred miles on 87 and then switched over to 93 for 1 tank before towing it around the same distance with 93. Barely a difference was felt. It was smoother on 93 under full load in passing situations, but it still did the job on 87. It only lasted 1.5 tanks on 93 because there was only 87 and 90 rec fuel at every gas station I passed on the second trip.
Mileage was about the same overall.

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[runner69]

Years before the ethanol mandate I remember reading an article in one of the big three car mags about this. (I'm not sure how ethanol affects mileage across octane ratings). Lower octane gas generally has more energy per gallon, so an engine could theoretically get better mileage, because it didn't use as much fuel/mile. Higher octane fuels have additives to avoid pre-ignition/spark knock, and those additives actually decrease the total amount of energy per gallon. That was back in the day when cars didn't have all of the knock sensors and uber-computer controls and sensors making sure the engine was running at its most efficient. The new Ranger can most likely sense the difference and run accordingly. It also knows that it can pump more fuel into the cylinders with 93 (decreases pre-ignition), hence the increase in power we've seen in these trucks with higher octane fuels.

I have a 1998 Ranger 4x4 with the 4.0. I currently get about 16 mpg on 87. It goes to 14 mpg on 93, and it does not run nearly as well (SOTP meter).

higher octane doesn't mean more energy, or BTU's, per gallon. higher octane only means it burns a little slower so it allows the ignition timing to be advanced and that keeps the spark knock down

 

[t4thfavor]

Premium is actually less volatile, which equates to less energy per unit of mass.

 

[JoedOH]

So, has anyone else done MPG comparisons? I will be trying regular on my next fill-up but wondered if anyone else has tried switching to lower octane.

 

[Jacob]

So, has anyone else done MPG comparisons? I will be trying regular on my next fill-up but wondered if anyone else has tried switching to lower octane.

I ran all three (87/89/91). Surprisingly, 89 got the best fuel economy (roughly 23.5). Regular got roughly 23 and premium got 21.9. I don’t understand it at all but yeah I did the math myself. Not using the computer. The computer told me I was getting 25.4 on 89 which was obviously off.
Honestly I just run premium. Seems to run the best IMO. Do whatever you feel works best for you at the end of the day.

 

[JoedOH]

And this experiment is over for me. I wouldn't care if I got 5 mpg more, I'm going back to Premium.

My first tank and there is a noticeable difference in performance that I don't like. I went to pass a car today and the truck just seemed to lug. It has never done that since I've owned it.

 

[rltriumph]

I run 91 for the main reason it doesn’t have ethanol in it where I am at. I still think the ethanol isn’t a great thing for engines. I may be wrong but it makes me sleep better at night.

 

[JoedOH]

In Ohio we can get non ethanol fuel but it's expensive. I couldn't afford to run it in a vehicle. Darn that was a disappointment today. I did not expect such a big difference in performance.

 

[ajohnson]

I towed my camper a few hundred miles on 87 and then switched over to 93 for 1 tank before towing it around the same distance with 93. Barely a difference was felt. It was smoother on 93 under full load in passing situations, but it still did the job on 87. It only lasted 1.5 tanks on 93 because there was only 87 and 90 rec fuel at every gas station I passed on the second trip.
Mileage was about the same overall.

Do you use a trailer brake for that? I'm looking into towing something similar but disappointed the tow package did not come with an integrated trailer brake.

 

[Frenchy]

Do you use a trailer brake for that? I'm looking into towing something similar but disappointed the tow package did not come with an integrated trailer brake.

I feel you on the lack of trailer brake controller. As for towing the weight? The truck does well in general. I towed my 1983 280ZX on a U-haul Auto transport(roughly 5,500lbs) and it did it just fine amd thankfully that had its own trailer brake. If you ask me I suggest towing with premium fuel(91 and up) over regular fuel. You do get better power(not much but enough) and therefore your overall efficiency goes up. MPG may not go up but then again these are gas engines, not Diesels. That is my input on this.

 

[t4thfavor]

Do you use a trailer brake for that? I'm looking into towing something similar but disappointed the tow package did not come with an integrated trailer brake.

Of course...

prodigy p3

 

[RangerDangerStranger]

Livernois says stock engine mapping is tied to octane, they say you will loose 15%? i think, moving from 91 to 87, So I am going to assume you lost maybe 10% (30hp) with the switch. Betting it effected your throttle response and caused you to drive in a more fuel efficient manner, lol. After I read that, i switched from 87 which was ho-hum, to 91, which is go boy go! Big difference, and my millage has suffered significantly.

 

[JoedOH]

Livernois says stock engi9ne mapping is tied to octane, they say you will loose 15%? i think, moving from 91m to 87, So I am going to assume you lost maybe 10% (30hp) wiht the switch. betting it effected your throttle response and caused you to drive in a more fuel efficient manner, lol. After ui read that, i switched form 87 which was ho hum, to 91, which is go boy go! big difference, and my millage has suffered significantly.

That's about what I observed. Throttle response is slower and it feels like HP is down too. Right now I'm trying to get down to a 1/2 tank so I can get the octane back up again.

I never ran 87 in this truck as I filled it with 91 as soon as I got it. After 18 months of higher octane it was very noticeable going to 87.

 

[Deleted member 1634]

I'm so glad I ran across this thread, because I thought I was going crazy! haha I've only filled up with premium (91) twice, both in the last couple weeks. The first time was when I was towing our camper just to see what difference it would make (small thing so more power isn't needed), and I noticed a 1-2mpg drop (~20 down to ~18.5). Second time was this current tank which I filled with premium because I was filling the small engine gas can (getting ready for the snowblower) and decided to just fill everything, truck and can, with the same stuff to make things easier. Now I'm getting much lower mileage (~24 down to ~20) on my work commuting. My driving style doesn't require the extra power and responsiveness some of you guys feel you need, so I'm definitely going back to 87 from here on out. Especially since it's almost a dollar cheaper per gallon ($2.75 vs $1.89) right now.

 

[JoedOH]

I'm so glad I ran across this thread, because I thought I was going crazy! haha I've only filled up with premium (91) twice, both in the last couple weeks. The first time was when I was towing our camper just to see what difference it would make (small thing so more power isn't needed), and I noticed a 1-2mpg drop (~20 down to ~18.5). Second time was this current tank which I filled with premium because I was filling the small engine gas can (getting ready for the snowblower) and decided to just fill everything, truck and can, with the same stuff to make things easier. Now I'm getting much lower mileage (~24 down to ~20) on my work commuting. My driving style doesn't require the extra power and responsiveness some of you guys feel you need, so I'm definitely going back to 87 from here on out. Especially since it's almost a dollar cheaper per gallon ($2.75 vs $1.89) right now.

I'll be honest, I haven't computed MPG on 87 yet but the truck is showing worse than 91 at 19.2. It showed 22.6 on 91.

Just because I use 91 doesn't mean I drive with a lead foot. Haven't gotten below 3/4 tank yet and when I get to 1/2 I'll fill up with 93. At that point I'll figure out MPG on the 87 oct. It's not looking as good as the higher octane.

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